A polyurethane containing polyoxyethylene side-chains is known and has been described in the patent literature. For example, EP 060,430 discloses a process for making a polyurethane having polyalkylene oxide side-chains characterised in that the polyalkylene oxide used as starting alcohol has at least two free hydroxyl groups separated by not more than 3 carbon atoms, which hydroxy groups react with diisocyanates. The polyurethane may be used to stabilise or destabilise foams, emulsions and dispersions. They may also be used with pigments and fillers. However, there is no mention that the polyurethane may be used as dispersants in non-aqueous media and especially in the preparation of non-aqueous millbases, paints and inks.
JP1995179801 A discloses a water soluble acrylic graft copolymer with a polyurethane backbone. The grafted copolymer has carboxylic acid functional groups that may be incorporated into the backbone or within the grafted acrylic portion.